department

(6)The term “department”, when used with respect to a military department, means the executive part of the department and all field headquarters, forces, reserve components, installations, activities, and functions under the control or supervision of the Secretary of the department. When used with respect to the Department of Defense, such term means the executive part of the department, including the executive parts of the military departments, and all field headquarters, forces, reserve components, installations, activities, and functions under the control or supervision of the Secretary of Defense, including those of the military departments.